We show that that the non-equilibrium spin polarization of one dimensional helical edge states at the boundary of a two dimensional topological insulator can dynamically induce a polarization of nuclei via the hyperfine interaction. When combined with a spatially inhomogeneous Rashba coupling, the steady state polarization of the nuclei produces backscattering between the topologically protected edge states leading to a reduction in the conductance which persists to zero temperature. We study these effects in both short and long edges, uncovering deviations from Ohmic transport at finite temperature and a current noise spectrum which may hold the fingerprints for experimental verification of the backscattering mechanism.
@article{arxiv.1207.7259,
title = {Backscattering Between Helical Edge States via Dynamic Nuclear Polarization},
author = {Adrian Del Maestro and Timo Hyart and Bernd Rosenow},
journal= {arXiv preprint arXiv:1207.7259},
year = {2013}
}